Platinum-doped proton exchange membrane, preparation method thereof and fuel cell

Abstract

The invention discloses a platinum-doped proton exchange membrane, a preparation method thereof and a fuel cell, and belongs to the technical field of fuel cells. The platinum black with catalytic activity and the perfluorinated sulfonic acid resin are fully mixed, and the platinum-doped proton exchange membrane which is uniform in thickness, high in conductivity and resistant to free radicals is prepared in a spraying mode. When the platinum-doped proton exchange membrane is applied to a fuel cell, the proton exchange membrane is doped with platinum with catalytic activity, so that the platinum-doped proton exchange membrane can react with oxygen in cross transmission, and the oxygen is prevented from penetrating through the platinum-doped proton exchange membrane to react with an anode to generate free radicals with oxidation activity; therefore, the influence of free radicals on the structure of the platinum-doped proton exchange membrane is reduced, and the platinum-doped proton exchange membrane has the advantages of long service life, high stability and strong conductivity.

Description

Technical Field

[0001] This invention belongs to the field of fuel cell technology, specifically relating to a platinum-doped proton exchange membrane, its preparation method, and a fuel cell. Background Technology

[0002] A proton exchange membrane fuel cell stack is a highly efficient power generation device. The membrane electrode assembly (MEA) is a key component where the internal electrochemical reaction occurs, comprising the proton exchange membrane, catalyst layer, and gas diffusion layer. The proton exchange membrane is crucial for connecting the anode and cathode catalyst layers, providing a channel for proton movement, and forming the circuit loop. During operation, the proton exchange membrane transfers proton ions from the anode catalyst layer, absorbs water and swells, and blocks electrons to prevent short circuits. Because fuel cells operate in a high-temperature, high-humidity, and high-potential environment, the proton exchange membrane must possess certain mechanical strength, high-temperature resistance, and resistance to electrochemical corrosion. Furthermore, during fuel cell operation, especially in hydrogen-oxygen systems, the cross-permeability of gases can cause the anode to generate oxidizing free radicals (H₂ + O₂ = H₂O₂) during the reaction, affecting the polymer branching structure of the proton exchange membrane and consequently its lifespan and stability.

[0003] Therefore, improving the electrochemical stability and conductivity of proton exchange membranes (PEMs) through modification, while ensuring mechanical strength and reducing fabrication difficulty, is crucial for the development, use, and stability of PEMs. Currently, PEM modification mainly includes the following aspects: 1) Chinese patent application CN115000437A discloses an enhanced PEM doped with a free radical scavenger and its preparation method, which improves the performance of the PEM by adding the free radical quencher nano-cerium oxide; 2) Chinese patent application CN110224166A discloses a phosphate-doped crosslinked polybenzimidazole high-temperature PEM and its preparation method, which promotes proton conduction by adding the organic polymer polybenzimidazole; 3) Chinese patent application CN101237054A discloses a doped crosslinked enhanced perfluorinated PEM and its preparation method, which promotes proton conduction by adding phosphate. However, the existing PEM modification methods suffer from problems such as short lifespan, low conductivity, and poor stability.

[0004] Therefore, it is necessary to provide a platinum-doped proton exchange membrane and its preparation method to overcome the shortcomings of the existing technology. Summary of the Invention

[0005] The purpose of this invention is to provide a platinum-doped proton exchange membrane, its preparation method, and a fuel cell. This addresses the problems of short lifespan, low conductivity, and poor stability in existing proton exchange membrane modification methods.

[0006] In a first aspect, the present invention provides a method for preparing a platinum-doped proton exchange membrane, comprising the following steps: S1, mixing perfluorosulfonic acid resin, solvent and platinum black to obtain a slurry; S2, dispersing the slurry to obtain a dispersed slurry; S3, spraying the dispersed slurry to obtain an intermediate membrane; S4, rolling the intermediate membrane to obtain a platinum-doped battery proton exchange membrane.

[0007] In this invention, the inventors discovered that by thoroughly mixing catalytically active platinum black and perfluorosulfonic acid resin and then applying the mixture via spraying, a platinum-doped proton exchange membrane with uniform thickness, high conductivity, and resistance to free radicals can be prepared. Furthermore, this platinum-doped proton exchange membrane exhibits a long lifespan and high stability, thus showing promising application prospects in fuel cells.

[0008] In some embodiments, in step S1, the mass ratio of perfluorosulfonic acid resin to platinum black is 1:(0.01-0.05), for example, it can be 1:0.01, 1:0.02, 1:0.03, 1:0.04, 1:0.05 or other ratios within this range.

[0009] In this invention, the inventors further discovered that by controlling the mass ratio of perfluorosulfonic acid resin to platinum black within a specific range, a platinum-doped proton exchange membrane with stronger conductivity and better resistance to free radicals can be obtained. If the doping content of platinum black is low, the conductivity and free radical resistance of the prepared platinum-doped proton exchange membrane will decrease. If the doping content of platinum black is too high, the platinum black will be unevenly dispersed and have poor utilization, which will also cause a decrease in the conductivity and free radical resistance of the platinum-doped proton exchange membrane.

[0010] In some implementations, in step S1, the solid content of the slurry is 10-30 wt%, for example, it can be 10 wt%, 15 wt%, 20 wt%, 25 wt%, 30 wt%, or other values ​​within this range.

[0011] In this invention, the inventors further discovered that controlling the solid content of the slurry within a specific range facilitates subsequent dispersion and spraying processes, resulting in a uniformly dispersed platinum-doped proton exchange membrane.

[0012] In some embodiments, in step S1, the solvent includes at least one of an inorganic solvent and an organic solvent; wherein the inorganic solvent includes deionized water, and the organic solvent includes at least one of methanol, ethanol, and isopropanol.

[0013] It is understood that the inorganic and organic solvents can be selected from conventional inorganic and organic solvents in the prior art according to actual application needs, as long as they can disperse the slurry and fully dissolve the platinum. In this invention, the inorganic solvent preferably includes deionized water, and the organic solvent preferably includes at least one of methanol, ethanol, and isopropanol.

[0014] In some embodiments, the solvent includes inorganic and organic solvents, and the mass ratio of inorganic to organic solvents is (0.5-1.5):(0.5-1.5), for example, it can be 0.5:0.5, 0.5:1, 0.5:1.5, 1:0.5, 1:1, 1:1.5, 1.5:0.5, 1.5:1, 1.5:1.5 or other ratios within this range.

[0015] It is understood that the ratio of inorganic solvent to organic solvent can be adjusted according to actual usage needs, as long as the slurry is dispersed and the platinum is fully dissolved. In this invention, the preferred mass ratio of inorganic solvent to organic solvent is (0.5-1.5):(0.5-1.5).

[0016] In some embodiments, in step S2, the dispersion treatment includes at least one of high-speed shear dispersion, ball milling dispersion, and ultrasonic oscillation dispersion, and the temperature of the dispersion treatment is 20-30°C, for example, it can be 20°C, 22°C, 24°C, 26°C, 28°C, 30°C or other values ​​within this range.

[0017] Understandably, the dispersion treatment can be carried out using conventional methods in the existing technology, as long as the slurry is sufficiently dispersed, based on actual application needs. Furthermore, by controlling the dispersion treatment temperature within a specific range, damage to the slurry structure caused by high temperatures can be avoided.

[0018] In some implementations, step S3 includes at least one of ultrasonic spraying, electrostatic spraying, and pneumatic spraying.

[0019] Understandably, the spraying process specifically includes feeding the dispersed slurry to the nozzle, and then using at least one of ultrasonic spraying, electrostatic spraying, or pneumatic spraying to spray the slurry onto a vacuum adsorption platform with a flatness of ±5μm. This vacuum adsorption platform has vacuum adsorption and heating functions to ensure the flatness of the product preparation process and the drying of the intermediate film. The vacuum adsorption method can be conventionally selected, such as porous ceramics or array-pore vacuum pump adsorption. The heating temperature range is 20-150℃, and the temperature does not exceed the glass transition temperature of the perfluorosulfonic acid resin.

[0020] In addition, during the spraying process, a cross-spraying path should be used, with the spacing between spray paths less than the spray diameter, ideally 2mm. The spraying length and width distance can be determined by the product's length and width, and should appropriately exceed the product's length and width. Masking should be used around the perimeter during spraying. Furthermore, multiple nozzles can be used in a continuous spraying mode. The number of spray passes depends on the product thickness; the thickness can be increased or decreased by stacking the sprays.

[0021] In some implementations, in step S4, the thickness of the platinum-doped battery proton exchange membrane is 5-30 μm, for example, it can be 5 μm, 8 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm or other values ​​within this range.

[0022] It is understood that the thickness of the proton exchange membrane in a platinum-doped battery can be adjusted according to actual usage needs. In this invention, the thickness of the proton exchange membrane in a platinum-doped battery is preferably 5-30 μm.

[0023] In a second aspect, the present invention provides a platinum-doped proton exchange membrane prepared using any of the above-described preparation methods.

[0024] In a third aspect, the present invention provides a fuel cell comprising the above-described platinum-doped proton exchange membrane.

[0025] In this invention, when a platinum-doped proton exchange membrane is applied to a fuel cell, because the proton exchange membrane is doped with catalytically active platinum, it can react with cross-transported oxygen (2Pt + O2 = 2PtO, PtO + 2H2O). + =Pt + (+H2O) prevents oxygen from passing through the platinum-doped proton exchange membrane and reacting with the anode to generate free radicals with oxidizing activity, thereby reducing the impact of free radicals on the structure of the platinum-doped proton exchange membrane. This results in the platinum-doped proton exchange membrane having the advantages of long life, high stability, and strong conductivity.

[0026] The beneficial effects of this invention are as follows: Unlike existing technologies, this invention prepares a platinum-doped proton exchange membrane (PEM) with uniform thickness, strong conductivity, and resistance to free radicals by thoroughly mixing catalytically active platinum black and perfluorosulfonic acid resin and then applying the mixture via spraying. When the PEM is applied to a fuel cell, the catalytically active platinum doping in the PEM allows it to react with cross-transported oxygen, preventing oxygen from reacting with the anode and generating oxidizing free radicals. This reduces the impact of free radicals on the structure of the PEM, resulting in advantages such as long lifespan, high stability, and strong conductivity. Attached Figure Description

[0027] Figure 1 This is a flowchart of the preparation method of the platinum-doped proton exchange membrane in this invention. Detailed Implementation

[0028] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0029] Experimental methods not specified in the examples are generally performed under conventional conditions and as described in the manual, or as recommended by the manufacturer. Unless otherwise specified, the general equipment, materials, reagents, etc. used are commercially available.

[0030] Please see Figure 1 The flowchart below illustrates the preparation method of the platinum-doped proton exchange membrane in this invention. Specifically, the preparation method of the platinum-doped proton exchange membrane includes the following steps: S1, mixing perfluorosulfonic acid resin, solvent, and platinum black to obtain a slurry; S2, dispersing the slurry to obtain a dispersed slurry; S3, spraying the dispersed slurry to obtain an intermediate membrane; S4, rolling the intermediate membrane to obtain the platinum-doped battery proton exchange membrane.

[0031] Example 1 A method for preparing a platinum-doped proton exchange membrane includes the following steps: S1. Disperse 25g of perfluorosulfonic acid resin in 75g of deionized water, then add 75g of isopropanol and 1g of platinum black (100% pure platinum) and disperse and mix to obtain a slurry with a solid content of 14.8wt%. S2. The slurry prepared in step S1 is subjected to high-speed shearing for 1 hour, while keeping the temperature during the shearing process below 30°C, to obtain the dispersed slurry. S3. Feed the dispersed slurry obtained in step S2 to the ultrasonic nozzle, set the feeding speed to 500 mL / min, and spray it onto the vacuum adsorption platform by spraying. Set the platform temperature to 110℃ and the platform flatness to ±5 μm. Ensure that the vacuum adsorption is turned on during the spraying process. Set the spraying distance to 12 cm long and 12 cm wide, the spraying row spacing to 2 mm, and spray crosswise 10 times to obtain the intermediate film. S4. The intermediate membrane obtained in step S3 is passed through a roller with a slit thickness of 8 μm and fully rolled to obtain a platinum-doped battery proton exchange membrane with a length and width of 10 cm and a thickness of 8 μm.

[0032] Example 2 A method for preparing a platinum-doped proton exchange membrane includes the following steps: S1. Disperse 25g of perfluorosulfonic acid resin in 75g of deionized water, then add 75g of isopropanol and 0.25g of platinum black (100% pure platinum) and disperse and mix to obtain a slurry with a solid content of 14.4wt%. S2. The slurry prepared in step S1 is subjected to high-speed shearing for 1 hour, while keeping the temperature during the shearing process below 30°C, to obtain the dispersed slurry. S3. Feed the dispersed slurry obtained in step S2 to the ultrasonic nozzle, set the feeding speed to 500 mL / min, and spray it onto the vacuum adsorption platform by spraying. Set the platform temperature to 110℃ and the platform flatness to ±5 μm. Ensure that the vacuum adsorption is turned on during the spraying process. Set the spraying distance to 12 cm long and 12 cm wide, the spraying row spacing to 2 mm, and spray crosswise 10 times to obtain the intermediate film. S4. The intermediate membrane obtained in step S3 is passed through a roller with a slit thickness of 8 μm and fully rolled to obtain a platinum-doped battery proton exchange membrane with a length and width of 10 cm and a thickness of 8 μm.

[0033] Example 3 A method for preparing a platinum-doped proton exchange membrane includes the following steps: S1. Disperse 25g of perfluorosulfonic acid resin in 75g of deionized water, then add 75g of isopropanol and 0.5g of platinum black (100% pure platinum) and disperse and mix to obtain a slurry with a solid content of 14.5wt%. S2. The slurry prepared in step S1 is subjected to high-speed shearing for 1 hour, while keeping the temperature during the shearing process below 30°C, to obtain the dispersed slurry. S3. Feed the dispersed slurry obtained in step S2 to the ultrasonic nozzle, set the feeding speed to 500 mL / min, and spray it onto the vacuum adsorption platform by spraying. Set the platform temperature to 110℃ and the platform flatness to ±5 μm. Ensure that the vacuum adsorption is turned on during the spraying process. Set the spraying distance to 12 cm long and 12 cm wide, the spraying row spacing to 2 mm, and spray crosswise 10 times to obtain the intermediate film. S4. The intermediate membrane obtained in step S3 is passed through a roller with a slit thickness of 8 μm and fully rolled to obtain a platinum-doped battery proton exchange membrane with a length and width of 10 cm and a thickness of 8 μm.

[0034] Comparative Example 1 In this comparative example, the preparation method of the proton exchange membrane is basically the same as that in Example 1, except that platinum black is not added in step S1.

[0035] Comparative Example 2 In this comparative example, the preparation method of the proton exchange membrane is basically the same as that in Example 1, except that the amount of platinum black added in step S1 is 0.1g.

[0036] Comparative Example 3 In this comparative example, the preparation method of the proton exchange membrane is basically the same as that in Example 1, except that in step S1, the amount of platinum black added is 2g.

[0037] Performance testing The conductivity of the platinum-doped proton exchange membranes prepared in Examples 1-3 and Comparative Examples 2-3, as well as the proton exchange membrane prepared in Comparative Example 1, was tested. The specific method is as follows: A sample with dimensions of 1 cm × 2 cm was cut, and two parallel wires were placed 1.5 cm apart on both sides. The sample was then fixed and immersed in distilled water for 60 min. The AC impedance spectrum of the proton exchange membrane immersed in distilled water was measured using the three-electrode method. The conductivity was calculated using σ = L / RS, where σ (S / cm) is the conductivity, L (cm) is the distance between the two parallel wires, and S (cm) is the conductivity. 2 R is the cross-sectional area of ​​the membrane between parallel conductors, and R is the fitted impedance (Ω). The results are shown in Table 1 below.

[0038] Table 1 Conductivity Test Results

[0039] As shown in Table 1, the platinum-doped proton exchange membranes prepared in Examples 1-3 exhibit good electrical conductivity. In Comparative Example 1, without the addition of platinum black, the electrical conductivity of the prepared proton exchange membrane decreased significantly. In Comparative Examples 2 and 3, the amount of platinum black added was either too low or too high, resulting in a certain degree of decrease in the electrical conductivity of the prepared platinum-doped proton exchange membranes. These results indicate that controlling the mass ratio of perfluorosulfonic acid resin to platinum black within a specific range can yield platinum-doped proton exchange membranes with stronger electrical conductivity.

[0040] The platinum-doped proton exchange membranes prepared in Examples 1-3 and Comparative Examples 2-3, as well as the proton exchange membrane prepared in Comparative Example 1, were assembled into a fuel cell. After the fuel cell had been running for a period of time, the platinum-doped proton exchange membranes and proton exchange membranes were removed and the membrane structure was observed. The results are shown in Table 2 below.

[0041] Table 2 Observation results of membrane structure

[0042] As shown in Table 2, the platinum-doped proton exchange membranes prepared in Examples 1-3 maintained a smooth membrane structure and exhibited good lifespan and stability after prolonged operation. In Comparative Example 1, without the addition of platinum black, the membrane structure showed some damage after prolonged operation, and the membrane's lifespan and stability decreased significantly. In Comparative Examples 2 and 3, the amount of platinum black added was either too low or too high, resulting in a relatively smooth membrane structure but a certain degree of decrease in membrane lifespan and stability after prolonged operation. These results indicate that controlling the mass ratio of perfluorosulfonic acid resin to platinum black within a specific range can yield platinum-doped proton exchange membranes with better resistance to free radicals.

[0043] In summary, this invention thoroughly mixes perfluorosulfonic acid resin and platinum catalyst, utilizes the hydrophilic properties of platinum to prepare a slurry with good uniformity, and then uses a spraying method to prepare a platinum-doped proton exchange membrane with uniform thickness, strong conductivity, and resistance to free radicals. Furthermore, the platinum-doped proton exchange membrane has a long lifespan and high stability.

[0044] It should be noted that all the above embodiments belong to the same inventive concept, and the descriptions of each embodiment have different focuses. Where the description in a particular embodiment is not detailed, please refer to the description in other embodiments.

[0045] The embodiments described above are merely illustrative of implementation methods of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A method for preparing a platinum-doped proton exchange membrane, characterized in that, Includes the following steps: S1. Mix perfluorosulfonic acid resin, solvent and platinum black to obtain a slurry; S2. Disperse the slurry to obtain a dispersed slurry; S3. Spray the dispersed slurry to obtain an intermediate film; S4. Roll the intermediate membrane to obtain a platinum-doped battery proton exchange membrane.

2. The method for preparing a platinum-doped proton exchange membrane according to claim 1, characterized in that, In step S1, the mass ratio of the perfluorosulfonic acid resin to the platinum black is 1:(0.01-0.05).

3. The method for preparing a platinum-doped proton exchange membrane according to claim 1, characterized in that, In step S1, the solid content of the slurry is 10-30 wt%.

4. The method for preparing a platinum-doped proton exchange membrane according to claim 1, characterized in that, In step S1, the solvent includes at least one of inorganic solvents and organic solvents; The inorganic solvent includes deionized water, and the organic solvent includes at least one of methanol, ethanol, and isopropanol.

5. The method for preparing a platinum-doped proton exchange membrane according to claim 4, characterized in that, The solvent includes inorganic solvents and organic solvents, and the mass ratio of the inorganic solvent to the organic solvent is (0.5-1.5):(0.5-1.5).

6. The method for preparing a platinum-doped proton exchange membrane according to claim 1, characterized in that, In step S2, the dispersion treatment includes at least one of high-speed shear dispersion, ball milling dispersion, and ultrasonic oscillation dispersion, and the temperature of the dispersion treatment is 20-30℃.

7. The method for preparing a platinum-doped proton exchange membrane according to claim 1, characterized in that, In step S3, the spraying process includes at least one of ultrasonic spraying, electrostatic spraying, and pneumatic spraying.

8. The method for preparing a platinum-doped proton exchange membrane according to claim 1, characterized in that, In step S4, the thickness of the platinum-doped battery proton exchange membrane is 5-30 μm.

9. A platinum-doped proton exchange membrane prepared by any one of claims 1-8.

10. A fuel cell, characterized in that, Includes the platinum-doped proton exchange membrane as described in claim 9.

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